This works for me until I turn my Xbox off. When I go back on the following day, it no longer is connected. My Xbox in the IP address section gives a different address when it’s wireless as to when it is wired. Is this normal?
Yes this is normal. The TPG router issues DHCP IP leases based on MAC address. The Xbox has a different MAC address for its Wireless and Wired interfaces. That is why your getting different addresses.
In the bottom picture below where you type the address it says to enable NAT function, where do I do this?
NAT is enabled by default. No need in setting this up.
You would need to configure a STATIC IP address on your XBOX in the network settings and this should fix this issue.
Please configure an IP address outside of the DHCP range of the router e.g. 192.168.1.10. You also need to enter 192.168.1.10 in the DMZ configuration of the TP-Link router.
Static IP configuration Instructions can be viewed here - https://support.ubi.com/en-GB/faqs/000025508/Setting-up-a-static-IP-address-for-Xbox-One
Hope this helps!